1. Field of the Invention
The invention relates to a compression device for an internal combustion engine, and more particularly to a turbine device with a variable flow for a vehicular turbocharger.
2. Description of the Related Art
In multi-cylinder engines, a double channeled turbine housing has been widely applied for employing the pulse energy produced by each opening of different cylinders. As shown in FIG. 1, a turbine of a conventional double channeled turbocharger includes: a turbine housing 1, an impeller 2, and a gas outlet 3. A flow channel of the turbine housing is divided into a left flow channel 4a and a right flow channel 4b by a middle partition 5.
In normal operating conditions, inlets of both the left flow channel 4a and the right flow channel 4b are connected to exhaust manifolds of different cylinders of the engine. The cylinders exhaust gas in the way of a pulse which flows into the left flow channel 4a and the right flow channel 4b and passes turbine nozzles; the gas flow finally reaches the turbine impeller 2 and does work in a flow channel of the turbine impeller 2 via expansion. Thus, the turbine impeller 2 is initiated into rotating and drives the compressor impeller to rotate via a turbine shaft, thereby achieving the supercharging of the engine. The gas after doing work flows into an exhaust main of the engine via the gas outlet 3.
However, if the double channeled turbine housing 1 is designed to match an engine at high operating conditions, when the engine is at a low operating condition, the gas flow is minimized. The flow channel of the turbine housing 1 has a relatively large volume, the pulse wave of the gas is correspondingly reduced, and thus, the pulse energy cannot be effectively used. If the double channeled turbine housing 1 is designed to match the engine at low operating conditions, the turbine housing 1 is relative small; and when the engine is at a high operating condition, a velocity of the flow inside the turbine is increased, and the flow loss is correspondingly increased. In the meanwhile, a relative small turbine housing has a poor performance of thermal load when the engine is at a high operating condition.
To satisfy the exhausting performance of high and low load of the engine and to improve the efficiency of the turbine, a plurality of turbine devices with variable cross section have been developed based on the double channeled turbine. However, the conventional turbine with variable cross section and the corresponding exhaust manifold of the engine are independently designed, so that the two are not well matched, thereby impacting the performance of the turbine. In the conventional turbine with variable cross section, the valve is arranged inside the turbine housing, which results in a flow loss at the valve. In the meanwhile, the conventional flow channels of the turbine housing are seldom well matched with the multi-cylinder engine, and a reasonable arrangement of the exhaust pulse is restricted.